1. Field of the Invention
This invention is directed to retrofit units for light fixtures, in general, and to retrofit units which permit fluorescent or similar light bulbs to replace incandescent light bulbs in a downlight-style or a cylinder-type fixture, in particular.
2. Prior Art
There are many types of lighting fixtures which are known in the art. These include recessed fixtures, surface mounted fixtures, track-light fixtures and the like. Most of the known light fixtures use incandescent light sources therein. However, incandescent light sources have a short life and are inefficient. The number of lumens generated per electrical watt consumed is not economical and is generally in the area of 14 to 17 lumens per watt. In addition, these types of light sources generally use a thin filament which glows when heated by electrical power, and tends to burn out or break rather easily.
Also, incandescent light sources tend to generate a large amount of heat which is given off into the surrounding area. This has the secondary shortcoming of producing heat in many places where excessive heat is not desired. Consequently, it becomes necessary to use air conditioning equipment or the like to eliminate this unwanted heat. Consequently, incandescent light sources tend to be energy consumers and wasters.
Several types of alternative light sources are known in the art. For example, fluorescent, high-pressure sodium and metal halide lamps and the like are typical. These light sources generally tend to operate quite efficiently and provide 50 to 120 lumens per watt. The lower wattages do not, as a rule, produce excess heat during operation.
However, these alternative light sources are normally not interchangeable with incandescent lamps or bulbs. For one thing, the different light sources may have different couplings. The “Edison-base” coupling which is common in the ordinary incandescent light fixture will not accept standard fluorescent fittings. Although single ended high pressure sodium and metal halide lamps are available and can be screwed into an Edison-base socket, they cannot be successfully operated because most arc discharge lamps require a ballast to operate the lamp. Since the ballast may be relatively large, it usually cannot be mounted within the interior of the existing fixture.
In order to convert an existing inefficient incandescent lighting system to a more efficient light source, it has been necessary to replace the existing lighting fixture with a totally new lighting fixture that incorporates the proper socket configuration and ballast assembly in a new fixture.
Consequently, it is highly desirable to develop light fixtures which permit these alternative light sources to be retrofitted into existing electrical system hardware efficiently and economically.
Generally cylindrical lighting fixtures (whether round or square in configuration) are a highly desirable and extensively used light fixture. Typically, a cylindrical fixture is mounted above a specific area upon which light is to be projected. The fixture may be wall or ceiling mounted or suspended from the ceiling by a mounting stem. A conventional electrical or Edison socket is mounted in the cylinder at the base or top end thereof.
The first generation of compact single ended fluorescent lamps became available more than 20 years ago. These lamps were initially low wattage, 5, 7, 9 lamps, e.g., watts. These lamps were followed by 13, 18, 26 watt lamps. These lamps were, typically, twin-tube or quad-tube designs. They were designed to run on magnetic ballast and used trace amounts of mercury to operate successfully. Recently, higher wattage lamps were developed, i.e., 32, 42 watts and the like as well as triple-twin-Tube lamps. Also, an amalgam component was added into the gas mixture in the gas mixture to optimize the light output at higher temperatures than the old mercury filled lamps.
Higher wattage lamps generate more heat. Excessive heat made it more difficult for fixture manufacturers to design fixtures that would run cool enough not to cause the lamps to fail prematurely.
In general, the newer amalgam lamps have helped alleviate the excessive heat condition, but thermo-problems are still a significant problem, especially in ceiling recessed down light fixtures with lamps burning in a “base up” position. That is, heat from the lamp operation rises, thus, elevating the temperature in the upper, closed end of the fixture where the amalgam pellet is located in the lamp. The cap area must be kept relatively cool because temperatures above 140° C. will result in short lamp life.
Conversely, the lamp reaches optimum efficiency when the lower portion of the lamp, or mixing chamber, (where a mixture of mercury and amalgam gases blend together) is at an elevated temperature. To optimize the performance of the lamp it is essential that a proper mixture of gases in the proper amount come together in the mixing chamber.
According to the GE product information for OEM's lamp performance, “The performance parameters, such as luminous output; lamp voltage and power depends on the mercury vapor pressure in the discharge tube. The mercury vapor pressure is a function of the thermal condition around the glass tubes and the amalgam.”